Bump actions/checkout from 5 to 6 (#765)

Author: dependabot[bot]

.github/workflows/ci_format.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: 'ros-industrial/industrial_ci@master'
         env:
           ROS_DISTRO: noetic

.github/workflows/reusable_ici.yml

@@ -35,10 +35,10 @@ jobs:
     steps:
       - name: Checkout ${{ inputs.ref }} when build is not scheduled
         if: ${{ github.event_name != 'schedule' }}
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Checkout ${{ inputs.ref }} on scheduled build
         if: ${{ github.event_name == 'schedule' }}
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: ${{ inputs.ref_for_scheduled_build }}
       - run: docker network create --subnet=192.168.56.0/24 ursim_net